 |
| Titel |
Groundwater vertical velocity from thermal data in aquifer recharge areas: first results on the Lanzo Fan (Piedmont, NW Italy) |
| VerfasserIn |
Diego Barbero, Domenico Antonio De Luca, Maria Gabriella Forno, Manuela Lasagna |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250127487
|
| Publikation (Nr.) |
 EGU/EGU2016-7369.pdf |
|
|
|
|
|
| Zusammenfassung |
| The aim of this study is the evaluation of groundwater vertical velocity from thermal data in
aquifer recharge areas. More specifically a particular solution of differential heat equation
able to determine the groundwater velocity was applied. The vertical component of the
velocity is an important parameter to estimate the time of the aquifer recharge of deep aquifer
for drinking water supply. The used method is developed through a statistical analysis on the
temperature measures collected in boreholes located in the Lanzo Fan, in the Piedmont Po
Plain (NW Italy).
The Lanzo Fan is a terraced alluvial fan, with an extension of about 300 km2, drained by
the Stura di Lanzo River. It results as an important recharge area for the aquifer of the western
Po Plain. An important water well field occurs in this fluvial fan: it represents one of main
water sources for Turin supply.
The sedimentary succession consists of a very thick Villafranchian complex, referred to
Piacenzian-Calabrian, that constitutes a multilayer aquifer. The Villafranchian complex is
covered by thin fluvial middle Pleistocene deposits (about 15-20 m thick), consisting of
gravel and sandy texture. The data were collected in the shallow aquifer hosted in the fluvial
deposits. Groundwater flow is directed from the recharge area to the final receptor
represented by Po River, flowing North of the Turin Hill. The piezometric surface of the
shallow aquifer, that follows the topographic surface, shows hydraulic gradient
varying from 1%, in the proximity of the apex of the fan, to 0.1%, in the distal
areas.
The average depth of the boreholes used for temperature measures is from 30 up to 50
meters. The measures were obtained by the use of probes equipped with sensors of
temperature and depth, with ±0.01 degree Celsius sensitivity on temperature. The
thermal logs profiles show a common trend characterized, in the first meters of
depth, by temperature fluctuations linked to seasonal oscillations, and then become
concave with a radius of curvature gradually more pronounced due to the aquifer
supply.
The development of an hydrogeological and physical model of heat transfer in a porous
and completely saturated sediments, using analytical equations of heat transport by
conduction and advection with stationary boundary conditions, allows us to estimate the
vertical component of the groundwater velocity. The statistical analysis of thermometric data,
returns a vertical velocity of about 10−8 m/s. |
|
|
|
|
|
|